So one of the disadvantage I accepted a long time ago when I first got the camera, is not being able to adjust aperture while in LiveView. I shoot mostly video with my D7000, so LiveView is everything.

I often use my 18-200, at mid zoom range, f5.6 or more closed, and at 1/30th to match framerate. As we all know f5.6 is as much as the lens opens at 200mm.

Not using LiveView in Manual (M) mode, at 1/30 and f5.6, I can freely zoom in and out and the camera is locked at f5.6 through the whole range. At the same time, I can fully predict the aperture behaviour if I'm wide open at f3.5 at 18mm and then zooming in to have it close to f5.6. All good.

Enter LiveView. All the same settings (f5.6 & 1/30), but when I adjust zoom, the aperture closes down F9 when I hit 200mm. If I turn on LiveView while already at 70mm, the aperture closes from f5.6 to f6.3. More lens travel, the more it closes. Predictable but odd.

And here's the kicker, so I start at f5.6 at 18mm, enter LiveView, zoom to 200mm and it closes to f9, THEN, I toggle LiveView on and off, and it reverts back to f5.6 at 200mm? What gives?

This is especially odd since the camera does not allow for aperture adjust while in LiveView!

I had a few months where I barely used the camera, but I swear I did not experience this behaviour before when shooting video. It's just such a standout quality. I am baffled! Is there some setting that messed up, because I can't find one. I feel like I'm going crazy.

I use the 18-200VR a lot and the next step is ALWAYS the 70-300VR Nikkor. It is an amazing lens. The 80-400VR for wildlife shots is a major disappointment and I parted company with mine when I found it could NOT focus very fast at all. Too bad Nikon STILL has not produced an update for the 80-400VR as it would sell so well it would be a huge step forward for them. I have tried everything in this range INCLUDING the 200-400 Nikkor which is NOT what I want for location shots. That lens is simply a wrist breaker and don't tell me that is whimping out as I spend many hours in the field with ag equipment that requires considerable strength to run safely....
the 200-400 though is very, very good. It is just VERY big for field work when you have anything else going on. Bottom line to Nikon: We need an update to the 80-400VR but the 70-300VR is a real workhorse!

Get the AF Nikkor 80-400mm f/4.5-5.6D ED VR. Good reach on DX (600mm-equivalent), if you can deal with its maximum f/5.6 aperture. No AF-S, but at least it has VR, plus a tripod collar (I use mine with monopod nearly 100% of the time). I was able to find a refurb for only $1,050. Anything faster will cost you quite a bit more.

i have the 18-200 and the kenko 1.4. Surprisingly, they work together including focus but you really need bright conditions as IQ gets really iffy even if you are shooting at F8==F11 but if you are only publishing on the web then it may be ok. still I find that it is more troublesome since you have stick the 1.4 tc on and the loss of light and snappy focus is uncomfortable. Its better and more convenient to use the 18-200 without the TC14 and just crop (and maybe upscale). once you go above 200mm you will need to learn telephoto techniques. I had the old 200-400mm F5.6 Tamron( sob! lost it! ) and its surprisingly sharp! But I needed to carry a good strong tripod and learn breathing and shutter release techniques etc...

My suggestion is you look into getting the 80-400 VR nikkor or the 70-300VR. I understand that the 70-300VR is used by some professional nature photographers as its light and mobile in the field. If you are into fauna you will need to learn "hunting" techniques to approach the wild life without spooking them. in either case a small sturdy tripod wont be a bad idea as you can use it to brace the camera against your waist if you want some mobility. in either case esp with the 70-300 you can crop/upscale. but remember if you are planing to crop/upscale you will still need to apply telephoto techniques as you are in effect using it like a 600mm lense.

Costa Rica + wildlife = shooting under the jungle canopy? If so, you are likely to find the 5.6 maximum f-stop on the 70-300 limiting. Too limiting? maybe. In fact, the f-stop on your 18-200 may be too limiting. See if you can go someplace to replicate the jungle lighting you may experience, such as a nearby forest or arboretum or botanic garden and try photographing flowers or leaves with your 18-200 lens set at 200mm. That may tell you something about f-stop, shutter speed, ISO, tripod or monopod needed to get sharp photos in that level of light. If you are photographing something like sea turtles on a beach you will have plenty of light. I think most people would want an f 2.8 telephoto lens to photograph under the jungle canopy but such a lens is outside your price range.

I have the 70-300 vr and have used it on thousands of images. You do have to be concerned at the longer focal lengths about shake. What I try to do is to shoot at about 1/1000 if at all possible, primarily by raising ISO, sometimes by opening up the aperture. I also try to shoot at f8, but this is not always possible. This lens is within your budget and I think you would find it usable and providing you with really good images.

tcole1983 said:
For the money you want to spend just get the Nikon 70-300 VR if you want more range and it will perform better than the 18-200 at 200 mm. Drops off after 200, but is still usable at 300 mm.

+1 Unless you are selling your images professionally the slight drop-off in sharpness is next to nothing.

Teleconverter should really only be used on Primes. With variable zooms there will be not enough light to get a good focus lock unless you are shooting onto direct sunlit subjects.

Just a note on expectations of sharpness: Make sure to set your shutter speed to at least the equal the length of your lens. The lack of doing so is 99% of softness issues that most experience. On a 200mm shot your optimal sharpness will probably be at 1/200sec shutter speed with an aperture at F11. I would let the auto ISO handle the rest.

Nikon 300mm f4 seems like a good idea but beware with a D7000 you will be shooting at 450mm and I doubt you can get sharp images hand holding that lens. You are going to need a tripod, or a monopod or use a bean bag or towel over a car window or lay it over a daypack or something to steady if. Better practice technique at home before you go so you see what it takes to get a sharp image at 450mm. It an't easy!

For the money you want to spend just get the Nikon 70-300 VR if you want more range and it will perform better than the 18-200 at 200 mm. Drops off after 200, but is still usable at 300 mm. If you want a better 300 mm lens then get the 300 F4.

Lastly if you just wanted it for the trip you could rent a lens. You can rent the 300 F4 for 10 days for something around $100 I believe.

I purchased a D7000 with the 18-200mm lens and and very happy with it in most situations. At 200mm it's a bit soft and I've seen a little bit of vignetting in the corners.

I am heading to Costa Rica in May and anticipate needing more reach to shoot wildlife. There is also high probability of low lighting situations in the jungle. I don't have the budget of a professional photographer. I originally thought to buy the Kenko Pro 300 1.4X teleconverter, but after much research learned that it's not a good match for my existing lens.

All that said, can anyone recommend a good, affordable option? I'd like to spend about $500, but it almost seems impossible for what I need to get out of a lens. So I can go as high as $1000. Thinking maybe a stronger telephoto lens and possibly add the teleconverter? Or looking for a used, better piece of glass? Or of course, there are the off brands (which I don't know much about). I'd appreciate any suggestions on both the glass and where to purchase it at a savings.